This study develops and tests a nonhuman primate model for the amnesic effects of electroconvulsive stimulation (ECS) and magnetic seizure therapy (MST). Electroconvulsive therapy (ECT) is the most effective treatment for major depression, but produces anterograde and retrograde amnesia. Like ECT, MST induces generalized seizures, but stimulates a localized region of cortex and may be associated with less severe cognitive effects. Prior to the administration of ECS or MST, rhesus macaques will be trained on a battery of tasks that will assess retrograde and anterograde amnesia, including serial probe recognition (working memory), spatial memory, and serial list learning and memory. Intracerebral EEG electrodes will measure the electrophysiological characteristics of electrically- versus magnetically-induced seizures. A within-subject cross-over design is planned, with daily ECS, MST, or sham treatments for 4 wks. This work tests the hypothesis that the cognitive effects of convulsive therapy may be lessened by the use of novel forms of seizure induction. As such, this work will provide the basis for future human trials contrasting the antidepressant efficacy and cognitive effects of MST and ECT.